W7CZ 


Vol.  III.  No.  3. 


January,  1907 


MILWAUKEE 

NORMAL  SCHOOL 

BULLETIN 


Physiographic  Modeli 


of 


Wi 


isconsm 


Pabliihed  Quarterly  by  the  State  Normal  School,  Milwaukee,  Wis. 

Enteied  June  15,  1905,  at  Milwavjue,  Wisconsin,  at  second  class  matter 

under  Act  of  Congress,  July  16,  1894. 


models 
■^graphy  of  Wisconsir 


Southern  Branch 
of  the 

University  of  California 

Lo8  Angeles 


Form  L-1 


A    DESCRIPTION    OF    MODELS 


ILLUSTRATING   THE 


Physical  Geography  of  Wisconsin 


^^'''•'^-"V  0;    CALiFOHNIA. 

ii-^£  ANGELES.  CALiF. 


BY 
E.  C.  CASE 


MILWAUKEE 


■7 


'^n 


MODELS  SHOWING  THE  PHYSICAL  GEOGRAPHY  OF  THE 
STATE  OF  WISCONSIN. 


^  These  models  were  constructed  in  the  laboratory  of  the  Depart- 

^   ment  of  Physical  Geography  and  Geology  of  the  State  Normal  School 

""    at   Milwaukee.     They  are   based   on  the   last   geological   map   of  the 

state,   published   in    Buckley's    "Building   Stones    of   Wisconsin,"    and 

have  the  same  horizontal  scale — 20  miles  to  the  inch.     The  vertical 

scale  is  exaggerated    100  times,  which   seems   an   enormous   amount, 

but  is  necessarv  to  bring  out  the  features  of  the  eastern  part  of  the 

state.     As  only  a  small  portion  of  the  state  has  been  mapped  by  the 

topographic  survey,  a  great  many  of  the  elevations  have  been  taken 

from  railroad  profiles,  data  given  by  the  first  Geological  Survey  of  the 

state,  and  by  the  U.  S.  Geological  Survey.    In  the  preparation  of  such 

a  small  scale  model  it  was  impossible  to  show  all  parts  of  the  state 

with  any  great  degree  of  detail;  the  attempt  has  been  rather  to  show 

the  features  in  a  broad  way,  making  rather  a  "sketch  model"  than  one 

^3.     with  pretensions  to  absolute  accuracy.     The  characteristic  features  of 

■  1"^    different  parts  of  the  state  have  been  indicated,  as,  for  instance,  the 

^       residual    mounds    of   the    southwestern    portion,    the    Baraboo    Ridge, 

and  the  elongated  ridges  and  lowlands  on  the  eastern  side  of  the  state. 

The  only  previous  attempt  to  make  a  model  of  the  state  was  by 
Prof.  King,  who  built  a  model  somewhat  larger  than  the  present  one, 
with  a  smaller  vertical  scale  and  on  which  he  attempted  to  indicate 
the  prominent  features.  These  models  are  now  rather  difficult  to 
obtain  and  are  too  large  for  ordinary  class  room  work. 

All  of  the  present  models  have  been  prepared  on  the  same  base, 
but  have  been  colored  differently  to  illustrate  different  features  of 
the  state's  Physical  Geography.  The  first  shows  only  the  Relief; 
the  second  shows  the  state  as  an  Ancient  Coastal  Plain;  the  third 
shows  the   Glacial  Deposits  and  the  Driftless  Area. 

The  following  descriptions  of  the  models  are  taken  largely  from 
Prof.  Case's  new  book,  "Wisconsin — Its  Geology  and  Physical  Geog- 
raphy," just  issued. 


THE  SIMPLE  RELIEF  MODEL. 

The  state  is  divided  between  two  slopes;  a  long  and  gentle  one 
to  the  south  and  a  short  and  more  precipitous  one  to  the  north.  The 
water  parting  between  these  two  slopes  is  very  indefinite,  for  the 
natural  slope  of  the  land  is  obscured  by  the  overlying  drift  of  the 
Glacial  period,  and  the  highest  area  of  the  state,  the  source  of  most 
of  the  rivers,  is  fiat  and  swampy,  so  that  the  tributaries  of  the  Mis- 
sissippi and  of  the  St.  Lawrence  often  head  in  the  same  swamp.  No 
line  can  be  drawn  between  the  headwaters  of  the  Montreal  river  and 
of  the  Flambeau,  a  tributary  of  the  Chippewa. 


Fig.  1.    Photograph   of  the   Relief-  Model 

Cut  Furnished  by  the  Central  Scientific  Co.,  of  Chicago 


The   crest   of  the   north   slope   of   the   state   is   about   thirty   miles 
south  of  the  shore  of  Lake  Superior,  is  formed  by  the  summit  of  the 


Penokee  and  Douglas  ranges.  In  many  places  the  slope  is  covered 
by  the  glacial  claj-  so  deeply  that  the  underlying  rock  is  not  visible, 
but  in  other  places  the  portion  adjacent  to  the  shore  has  been  washed 
free  from  the  glacial  material  and  the  sandstone  stands  out  in  wave- 
cut  bluffs.  The  rivers  running  down  this  slope  are  slow  and  sluggish 
at  their  headwaters,  but  as  they  gain  the  edge  of  the  slope  they  plunge 
down  in  a  series  of  falls  and  rapids  to  the  fiat  land  along  the  shore; 
near  their  mouths  many  of  them  are  again  slow.  Where  they  flow 
over  the  soft  sandstone  they  have  cut  deep  gorges  almost  to  the 
water's  edge.  Many  of  the  streams  have  built  up  large  delta  deposits 
at  their  mouths  over  which  they  now  wander  through  swamps  and 
winding  channels. 

The  southern  slope  is  long  and  very  gentle,  extending  even  into 
Iowa  and  Illinois.  It  is  subdivided  by  a  low  and  irregular  divide  into 
two  parts;  an  eastern  and  a  western.  The  waters  of  the  western 
slope  flow  into  the  Mississippi  and  so  2,000  miles  and  more  to  the  Gulf 
of  Mexico;  the  waters  of  the  eastern  slope  flow  into  Lake  Michigan 
and  to  the  St.  Lawrence  and  the  North  Atfantic  ocean,  an  even 
greater  distance. 

Near  the  north  line  of  the  state  is  the  Penokee  Ridge,  a  long 
range  of  low  hills  which  stand  up  above  the  surrounding  country 
because  their  superior  hardness  has  enabled  them  better  to  resist  the 
attack  of  the  weather;  through  the  ridge  from  north  to  south  is  cut 
the  Penokee  Gap,  where  the  Bad  river  finds  its  way  from  the  swampy 
uplands  to  the  shore  of  Lake  Superior.  The  Penokee  Ridge  was 
formerly  called  the  highest  part  of  the  state,  but  it  is  now  known 
that  the  summit  of  Rib  Hill,  at  Wausau,  1,940  feet  above  the  level  of 
the  sea.  is   higher. 

From  the  highland  of  the  north  central  part  of  the  state  the 
rivers  run  in  a  distinctly  radial  manner,  giving  a  splendid  illustra- 
tion of  the  "consequent"  condition. 

South  of  the  highland  there  is  a  broad  lowland  extending  across 
the  state  in  a  crescentic  shape  from  east  to  west.  The  crescent  is 
broader  in  the  middle  and  narrows  towards  either  extremity.  This 
is  the  sandstone  area  of  Wisconsin  and  it  owes  its  condition  as  a 
lowland  to  the  rapid  disintegration  of  the  soft  sandstone.  The  pres- 
ence of  this  lowland  is  of  the  greatest  importance  to  the  state,  for 
it  is  here  that  all  the  waters  of  melting  snow  and  rain  enter  the 
ground  to  appear  farther  south  in  the  artesian  wells  for  which  the 
state  is  famous;  nor  does  it  cease  there,  for  the  artesian  wells  of  the 
adjacent  portions  of  Iowa  and  Illinois  derive  their  supply  from  the 
same  source. 


The  eastern  part  of  the  state  is  divided  between  long  ridges  and 
lowlands  parallel  to  the  shore  of  Lake  Michigan.  The  westernmost 
ridge  lies  along  the  border  of  the  sandy  lowland  and  separates  it  from 
a  second  lowland  to  the  east  in  which  lies  Green  Bay,  the  Lower 
Fox  river,  Lake  Winnebago,  Horicon  Marsh,  and  the  Rock  river  as 
far  south  as  Watertown.  This  ridge  is  low  and  irregular  and  is 
crossed  by  several  streams,  notably  the  Fox  and  the  Wolf  rivers. 
It  hardly  anoears  on  the  surface  as  a  ridge  and  might  easily  be  over- 
looked by  one  not  aware  of  its  presence;  the  glacial  drift  lies  deep 
upon  its  surface  and  the  rocks  peep  out  only  occasionally. 

The  second  lowland,  which  may  well  be  called  the  Green  Bay 
Lowland,  owes  its  presence  in  part  to  the  erosive  action  of  rivers  in 
pre-glacial  time  and  in  part  to  the  action  of  the  ice,  which  sent  a 
long  arm  down  this  valley  and  deepened  it  and  shaped  it  to  its  pres- 
ent form. 

The  eastern  side  of  the  Green  Bay  Lowland  is  formed  by  the 
outcrop  of  a  layer  of  heavy  limestone  which  faces  to  the  west  in  a 
steep  bluff,  but  slopes  very  gently  downward  to  the  east.  The  upper 
surface  of  the  eastern  slope  is  covered  by  the  glacial  debris,  so  that 
the  rock  does  not  appear  on  the  surface  and  there  is  a  false  appear- 
ance of  abruptness  in  places;  the  great  terminal  moraine  of  the 
Green  Bay  peninsula  lies  on  the  gentle  slope.  On  this  gentle  eastern 
slope  the  rivers  flow  to  Lake  Michigan;  in  many  cases  the  accumula- 
tion of  glacial  debris  causes  them  to  run  a  considerable  distance 
parallel  to  the  shore  before  entering  the  lake. 

The  southwestern  part  of  the  state  is  totally  different  from  the 
eastern,  the  rocks  lie  nearly  horizontal  in  the  ground,  and  the  rivers 
in  cutting  down  their  channels  have  not  worked  the  land  out  into 
long  lowlands  and  ridges,  but  have  cut  straight  down  through  hard 
and  soft  alike  as  they  came  to  it,  and  the  course  of  the  valleys  is 
accidental.  This  has  resulted  in  deeply  incised  valleys,  which  have 
cut  the  land  up  into  isolated  blocks  of  land  of  irregular  form.  The 
deep  valley  of  the  Wisconsin  river  cuts  off  a  region  of  very  rough 
land  on  the  north  from  a  less  deeply  dissected  region  on  the 
south.  The  north  edge  of  the  plateau  to  the  south  of  the  Wisconsin 
river  is  the  celebrated  Military  Ridge,  along  which  ran  the  military 
road  west  from  Madison;  it  is  now  occupied  almost  exactly  by  the 
Chicago  and  North-Western  railroad.  The  most  prominent  blocks  of 
the  dissected  plateau  south  of  the  Wisconsin  river  are  between  the 
Platte,  the  Sugar  and  the  Pecatonica  rivers.  On  the  summit  of  these 
blocks  lie  the  residual  mounds,  Blue  Mounds,  Platte  Mounds,  and  the 
Sinsinnawa  mound.  These  show  the  height  to  which  the  land 
reached  before  its  degradation. 


WISCONSIN  AS  AN  ANCIENT  COASTAL  PLAIN. 

The  second  of  the  models  shows  Wisconsin  as  an  Ancient  Coastal 
Plain,  as  described  by  Prof.  W.  M.  Davis  of  Harvard.  In  a  broad 
way  the  structure  of  the  state  is  very  simple;  it  consists  of  a  central 
mass  of  hard  igneous  rock  formed  in  the  earliest  geological  period,  the 
Archean.  This  central  mass  is  surrounded  on  all  sides  by  layers  of  more 
or  less  horizontal  sedimentary  rocks,  shales,  sandstones,  limestones, 
etc.  The  central  mass  of  hard  rocks  originally  stood  up  as  an  island 
or  peninsula  in  the  ocean  and  the  sedimentaries  were  deposited  on 
the  floor  of  the  ocean  around  the  island;  they  are  made  up  of  debris 
formed  by  the  degradation  of  this  or  neighboring  islands,  in  the 
adjacent  parts  of  Canada,  Minnesota  and  Michigan. 

The  edges  of  all  the  continents  today  present  a  very  similar 
appearance  below  the  water  line.     They  are  surrounded  by  an  area  of 


Fk;.  2.       PHOTOfVRAPH  OF  MODKL  ShOWINT,   WISCONSIN  AS  AN   AnCIKNT    CoASTAI,    Pi.AIN 

Cut  Furnished  by  the  Central  ScientilTc  Co.,  of  Chicay:o 


8 

gradually  deepening,  shallow  water  which  extends  out  from  the  wa- 
ter's edge  for  varying  distances,  but  which  terminate  by  a  sudden 
deepening  at  about  the  point  where  the  water  reaches  a  depth  of  100 
fathoms  (600  feet).  The  area  of  shallow  water  is  known  as  the  Con- 
tinental Shelf,  the  area  of  sudden  deepening  is  called  the  Continental 
Slope,  and  the  deeper  portion  of  the  ocean  beyond,  of  an  average 
depth  of  two  and  one-half  miles,  is  referred  to  as  the  Oceanic  Plateau. 
The  Continental  Slope  is  regarded  as  the  true  edge  of  the  continent 
and  the  Continental  Shelf  is  potentially  a  portion  of  the  land,  for  it 
is  elevated  and  depressed,  geologically  speaking,  today  and  tomorrow, 
and  the  deposits  upon  it  are  the  debris  of  the  land.  When  a  portion 
or  all  of  the  Continental  Shelf  is  raised  above  the  surface  of  the 
water  the  flat  plain  resulting  is  referred  to  as  a  Coastal  Plain. 

Upon  the  Continental  Shelf  are  deposited  the  sands,  clays  and 
limey  muds  that  become  the  sandstones,  shales  and  limestones  of  the 
Coastal  Plain  when  the  land  is  elevated.  The  deposits  from  the  land 
rarely  reach  beyond  the  edge  of  the  Continental  Shelf  and  the  "deeps" 
of  the  ocean  are  rarely  raised  to  the  surface  to  form  land,  so  that 
there  are  few  rocks  that  can  be  recognized  as  formed  of  deep  water 
deposits. 

It  is  in  this  wise  that  all  the  sea  coast  portion  of  the  eastern 
tier  of  states  has  been  formed.  The  "Atlantic  Coastal  Plain,"  lying 
between  the  sea  and  the  foot  of  the  Appalachian  Mountains,  was  at 
one  time  under  shallow  water  and  was  built  up  of  the  debris  from  the 
degradation  of  the  Appalachian  Mountains,  just  as  the  bottom  of  the 
ocean  adjacent  to  the  present  coast  line  is  receiving  deposits  today. 

In  the  alternate  elevations  and  submergences  the  State  of  Wiscon- 
sin went  through  much  the  same  history  as  the  Atlantic  Coastal 
Plain;  the  seas  surrounding  the  old  Archean  land  mass  were  mostly 
so  shallow  as  to  be  regarded  as  a  Continental  Shelf  and  on  their  bot- 
toms were  laid  down  the  debris  from  the  land  in  the  form  of  clays, 
sands  and  calcareous  muds  which,  when  the  land  was  elevated,  were 
hardened  into  the  shales,  sandstones  and  limestones  of  the  state. 
The  similarity  of  the  origin  and  history  between  the  State  of  Wis- 
consin and  the  Atlantic  coast  is  very  apparent;  only  our  state  passed 
through  its  history  millions  of  years  ago  and  the  Atlantic  coast  has 
still  to  complete  its  cycle  of  development.  Wisconsin  has  very  prop- 
erly been  described  by  Davis  as  an  "Ancient  Coastal  Plain." 

A  Coastal  Plain  may  result  from  the  elevation  of  the  Continental 
Shelf  in  two  ways.  (1)  Either  it  may  be  raised  horizontally  upward 
by  a  single  direct  movement  of  the  earth,  which  will  result  in  a  flat 
expanse  made  up  of  horizontal  layers  of  varying  hardness;  or,  (2)  it 
may   be   lifted   by   single   or   successive    movements    so   that    its   inner 


landward  end  is  higher  than  the  outer;  this  will  cause  the  layers  to 
be  tilted  in  the  ground  and  the  edges  will  appear  on  the  surfaces  as 
successive  parallel  belts.  As  soon  as  the  Coastal  Plain  appears  above 
the  surface  of  the  water  it  is  exposed  to  the  degrading  forces  of  nature 
and  the  rivers  begin  to  wear  down  into  it.  When  the  strata  are  tilted 
the  edges  of  the  hard  and  soft  layers  come  to  the  surface  alternately 
and  the  rivers  cut  down  into  the  soft  layers,  leaving  the  harder  ones 
standing  up  as  ridges.  The  ridges  thus  formed  with  one  slope  short 
and  steep  and  the  other  long  and  gentle  are  called  "Cuesta"  ridges. 
This  is  exactly  what  has  happened  in  eastern  Wisconsin  and  explains 
the  presence  of  the  ridges  and  lowlands.  When  the  rocks  are  more 
horizontal  the  rivers  cut  straight  down  and  there  is  an  irrcgularit}''  of 
the  topography,  as  explained  above  this  is  the  condition  of  south- 
western  Wisconsin. 

The  layers  of  sedimentary  rock  which  build  up  the  state  are 
from  below  upwards,  the  Potsdam  sandstone  of  the  Cambrian  divi- 
sion of  geological  time,  the  Lower  Magnesian  limestone,  the  St.  Peter's 
sandstone,  the  Galena  and  Trenton  limestones,  the  Cincinnati  shale 
of  Ordovician  time,  the  Clinton  iron  ore,  and  the  Niagara  lime- 
stone of  the  Upper  Silurian  time,  and  the  Hamilton  shale  of  the 
Devonian  time.  These  show  a  notable  alternation  of  hard  and  soft 
layers. 


Fig.  3.    Cro.ss  Section  of  State  from  Superior  to  Milwaukee   Showing 
Arrangement  of  the  Strata 


The  Potsdam  sandstone,  the  St.  Peter's  sandstone,  the  Galena 
limestone  and  the  Cincinnati  shales  arc  softer,  and  the  Archean 
crystallines,  the  Lower  Magnesian,  and  the  Niagara  limestone  are 
harder. 

In  accordance  with  the  principles  of  erosion  described  above  the 
tilted  rocks  of  the  eastern  portion  of  the  state  have  been  sculptured 
into  long  ridges  with  their  steeper  faces  toward  the  old  land  to  the 
north  and  west  and  separated  by  lowlands;  the  horizontal  rocks  of  the 
southern  part  have  been  sawn  apart  into  isolated  blocks.  This  gen- 
eral conception  of  the  degradation  of  the  state  controlled  by  the 
structure  of  the  underlying  rock  will  enable  the  student  to  get  a 
better  understanding  of  the  details  of  different  portions. 


10 

The  model  shows  the  surface  conditions  broadly.  The  Potsdam 
sandstone  lying  directly  upon  the  Archean  rocks  has  yielded  rapidly 
to  the  degrading  forces  and  has  been  worked  out  into  a  broad  low- 
land over  the  central  portion  of  the  state.  The  fact  that  the  outcrop 
of  this  porous  sandstone  has  been  reduced  to  a  lowland  and  that 
below  the  surface  it  slants  away  to  the  south  and  east  below  the 
impervious  Lower  Magnesian  limestone,  is  the  important  and  deter- 
mining factor  in  the  presence  of  the  artesian  waters  of  the  southern 
part  of  the  state,  and  of  Illinois  and  Indiana  as  well.  This  depressed 
area  is  the  Inner  Lowland  of  Wisconsin. 

Overlying  the  soft  Potsdam  sandstone  is  the  harder  Lower  Mag- 
nesian  limestone;  formerly  it  extended  much  farther  to  the  north,  but 
a  good  portion  has  been  removed  in  the  making  of  the  Inner  Low- 
land. The  outcrop  of  the  limestone  is  a  low  cuesta  ridge  with  its 
steeper  face  to  the  west  and  north.  It  does  not  show  as  a  bluff  on 
the  surface  because  it  is  largely  obscured  by  the  covering  layers  of 
glacial  drift,  but  its  course  is  marked  by  the  presence  of  a  line  of 
gently  rising  hills  from  the  north  side  of  which  the  limestone  projects 
at  intervals.  The  course  of  this  ridge  is  through  Marinette,  Oconto, 
Shawano,  Outagamie,  Winnebago,  Green  Lake,  and  Columbia  coun- 
ties. In  the  last  named  county  the  rocks  have  become  nearly  hori- 
zontal, so  the  rivers  no  longer  recognize  it  as  a  determining  factor  in 
their  course.  North  of  the  lower  Wisconsin  river,  in  the  triangle 
between  it  and  the  La  Crosse  and  Baraboo  rivers,  the  Lower  Magne- 
sian  limestone  appears  capping  the  tops  of  hills  of  horizontal  rock, 
but  because  of  the  horizontality  the  hills  are  isolated  blocks,  not 
continuous  ridges.  South  of  the  Wisconsin  the  Lower  Magnesian 
is  covered  by  the  rocks  of  higher  formation  and  is  nearly  horizontal, 
but  there  is  a  slight  dip  to  the  south;  this  region  is  a  distinct  high- 
land, deeply  trenched  by  the  rivers  which  run  over  it  in  an  irregular 
manner,  for  there  is  not  slope  enough  to  the  rocks  to  determine  their 
course,  but  on  the  north  the  edge  of  the  highland  is  marked  by  a 
steep  bluff  which  faces  to  the  north  and  overlooks  the  W^isconsin 
river  which  flows  at  its  foot.  The  steep  face  has  been  formed  by  the 
Wisconsin  river  shifting  slowly  to  the  south,  following  the  slight  dip 
of  the  layers  as  it  wore  out  its  bed  in  the  soft  Potsdam  sandstone. 
The  crest  of  this  bluflF  is  the  celebrated  Military  Ridge,  so  called  be- 
cause of  the  military  road  that  ran  along  in  the  early  daj-s  of  the 
state.  It  is  marked  today  almost  exactly  by  the  course  of  the  Chicago 
and  Xorth-Western  railroad  from  Madison  to  Dodgeville.  This  is  the 
inner  or  first  cuesta. 

Overlying  the  hard  rocks  of  this  cuesta  are  the  softer  rocks  of  the 
Galena    limestone    an<l    the    Cincinnati    shales.     In    the    eastern    part 


11 

of  the  state  these  have  been  excavated  into  a  long  lowland  parallel 
to  the  inner  cuesta,  running  through  Marinette,  Oconto,  Outagamie, 
Calumet,  Winnebago,  Brown,  Fond  du  Lac,  Dodge,  Jefferson,  Rock 
and  Walworth  counties.  The  course  of  the  lowland  is  marked  very 
plainly  by  the  position  of  Green  Bay,  the  Lower  Fox  river.  Lake 
Winnebago,  the  Horicon  marsh  and  the  Rock  river  as  far  south  as 
Watertown.  As  in  the  Inner  Lowland  and  the  First  cuesta  the  north- 
ern end  where  the  rocks  are  most  sharply  tilted  is  the  most  clearly 
defined.  The  valley  of  the  Lower  Fox  river  is  excavated  in  the  soft 
Cincinnati  shales,  so  that  it  has  very  low  walls  on  the  west  and  the 
bottom  is  very  broad,  but  the  eastern  side  is  marked  by  the  abrupt 
cliffs  of  the  steep  face  of  the  outer  cuesta  formed  by  the  overlying 
Niagara  limestone.  The  whole  of  the  outer,  or  Green  Bay,  lowland 
has  the  same  steep  face  of  limestone  from  the  extremity  of  Green 
Bay  on  the  north  to  a  point  nearly  west  of  Milwaukee  on  the  south. 

The  east  shore  of  Green  Bay  is  formed  by  a  line  of  bluffs  from 
100  to  200  feet  high  on  the  average,  but  reaching  as  much  as  400  feet 
in  places;  these  bluffs  are  nearly  vertical  and  have  been  sculptured 
by  the  weather  into  peaks  and  pinnacles,  isolated  crags  and  bluffs, 
that  give  to  the  shore  a  unique  beauty.  South  of  Green  Bay  on  the 
east  shore  of  Lake  Winnebago  and  as  far  south  as  Horicon  in  Dodge 
county  the  outcrop  of  the  limestone  still  forms  a  ridge  though  much 
reduced  in  height.  It  is  traceable  in  the  local  names,  Winnebago 
Ridge  and  "the  ledge."  Farther  south  the  lowland  area  is  less  appar- 
ent and  the  ridge  forming  its  eastern  face  becomes  lower  until  in  the 
town  of  Ashippun  in  Dodge  county,  about  opposite  Milwaukee,  it  dis- 
appears. The  ridge,  with  its  steep  western  face,  is  known  as  the  sec- 
ond or  Niagara  cuesta;  its  eastern  face  is  a  gentle  slope  to  the  shores 
of  Lake  Michigan,  although  the  surface  appears  far  from  gentle  in 
many  places,  being  covered  by  the  highly  irregular  superficial  deposits 
of  the  great  terminal  moraine.  The  slope  gradually  broadens  from 
the  northern  point  of  Door  county,  where  the  waters  of  Green  Bay 
and  Lake  Michigan  meet,  to  the  southern  edge  of  the  state,  where  it 
is  about  40  miles  wide. 

Far  to  the  west  in  the  Platte  and  Blue  Mounds  we  have  evidence 
of  the  former  extension  of  the  Niagara  limestone  over  the  southern 
portion  of  the  state,  for  the  tops  of  these  mounds,  many  feet  above 
the  surrounding  country,  are  capped  with  it  and  the  underlying  for- 
mations show  in  the  sides  of  the  mounds;  evidently  the  rocks  of  the 
Niagara  period  at  one  time  covered  all  the  intervening  part  of  the 
state  and  have  been  removed  by  the  processes  of  degradation  up  to 
the  present  limits  of  the  cuesta  ridge. 


12 

THE  MODEL  REPRESENTING  THE  GLACIAL  CONDITIONS 
IN  WISCONSIN. 

A  glacier  is  any  mass  of  ice,  consolidated  from  accumulated  snow, 
that  moves  by  its  own  initiation  over  the  ground;  usually  it  is  of 
good  size,  but  many  masses  of  small  size  clinging  to  the  sides  of 
mountains  have  a  motion  which  brings  them  within  the  definition. 
The  motion  is  very  slow,  rarely  exceeding  a  few  feet  a  day  (as  much 
as  100  feet  a  day  has  been  recorded,  but  this  is  regarded  as  highly 
exceptional).  Chamberlin  and  Salisbury  state  that  the  ice  cap  of 
Greenland  probably  does  not  advance  more  than  one  foot  a  day  on 
the  average.  The  origin  of  motion  in  the  masses  of  ice  is  an  un- 
solved problem,  but  we  know  it  does  move,  and  moves  in  a  manner 
comparable  to  that  of  a  very  viscous  body.  The  best  analogy  is  that 
of  a  barrel  of  tar  which  has  been  overturned  on  a  warm  day;  the  tar 
streams  slowly  from  the  barrel  and  drags  itself  stiffly  forward  over 
the  irregularities  of  the  surface,  but  eventually  accommodates  itself 
to  the  surface  as  perfectly  as  water  could  and  acts  upon  every  inch 
of  the  ground.  So  with  the  apparently  brittle  ice;  if  it  is  given  time 
it  moulds  itself  in  its  slow  advance  to  the  most  intricate  irregularities 
and  searches  out  every  exposed  surface  for  its  action.  Almost  every 
problem  of  glaciology  can  be  answered,  qualitatively  at  least,  by 
imagining  what  would  be  the  action  of  the  flowing  mass  of  tar  over 
the  same  surface. 

For  some  reason,  probably  a  combination  of  elevation  of  the 
surface  and  alteration  in  the  composition  of  the  atmosphere,  the 
climate  of  the  geological  period  just  preceding  the  present  was  re- 
duced so  much  that  great  quantities  of  snow  accumulated  in  several 
places  in  the  northern  hemisphere  and  slowly  spread  in  all  directions 
from  these  centers.  It  is  a  great  mistake  to  suppose  that  the  ice 
of  the  glacial  time  accumulated  at  the  north  pole  and  spread  evenly 
to  the  south  in  all  directions;  instead  the  ice  accumulated  in  distinct 
areas  rather  far  south  and  spread  north  as  well  as  east,  west  and 
south.  In  North  America  there  were  three  such  centers,  an  eastern 
just  east  of  Hudson's  Bay  suoporting  the  Labrador  ice  sheet,  a 
middle  just  to  the  west  of  Hudson's  Bay  from  which  spread  the 
Keewatin  sheet,  and  a  western  in  the  mountains  about  the  same  lati- 
tude, supporting  a  smaller.  Cordillcran  sheet.  It  is  with  the  eastern- 
most of  these,  the  Labrador  sheet,  that  we  have  most  to  do,  for,  with 
a  single  and  trifling  exception  it  is  the  only  one  which  entered  the 
limits  of  the  state. 

The  advance  of  the  ice  over  the  state  was  in  a  manner  very 
different  from  that  usually  pictured  by  students.     We  have  seen  that 


13 

it  did  not  originate  as  a  single  cap  at  the  north  pole  and  advance 
uniformly  to  the  south  over  all  parts  of  the  earth;  neither  did  it 
advance  with  an  unbroken  front  to  its  farthermost  limits  and  then 
retreat.  Its  movement  was  rather  a  succession  of  advances  and 
retreats,  no  single  movement  covering  exactly  the  same  ground  as 
the  others  nor  having  the  same  extent  to  the  southward.  The  differ- 
ent stages  of  advance  have  been  called  invasions  and  have  received 


Fig.  4.     Photocraph  op-  the  Model  Illustrating  the  Glacial  Conditions 

Cut  Furnished  by  the  Central  Scientific  Co..  of  Chicago 


names  suggested  by  the  states  or  regions  in  which  they  had  their 
maximum  development;  thus  six  different  invasions  have  been  made 
out  which  are  called  the  Alberton,  Kansan,  Illinoisan,  lowan,  Early 
Wisconsin  and  Late  Wisconsin.  It  is  the  sum  of  these  different  inva- 
sions that  is  spoken  of  as  the  Ice  Age  and  the  line  joining  the  farther- 
most extent  nf  each  and  all,  is  snokcn  of  as  the  snutlu-rn   limit   of  the 


14 

ice.  The  criteria  for  distinguishing  between  two  events  so  closely 
connected  in  time  as  two  of  these  invasions  are  so  obscure,  involving 
the  nice  balancing  of  evidence  furnished  by  the  appearance  of  soils, 
the  amount  of  erosion  and  the  accumulation  of  vegetable  debris  that 
it  is  often  beyond  the  power  of  any  but  the  expert  to  determine  the 
separation.  The  state  was  visited  by  at  least  two  which  have  left 
recognizable  the  traces,  an  earlier  invasion,  perhaps  the  lowan  or 
even  the  Kansan,  and  the  last,  the  Wisconsin  invasion. 

The  forward  movement  of  the  ice  over  the  state  in  the  different 
invasions  was  not  that  of  an  irresistible  mass  with  a  straight  unbroken 
front  which  overwhelmed  everything  in  its  path,  but  rather  that  of  a 
plastic  mass  which  accommodated  itself  to  the  surface  and  divided 
to  pass  around  obstacles,  doing  its  work  of  erosion  in  the  softer  rocks 
and  leaving  the  harder  comparatively  untouched.  In  order  to  under- 
stand the  form  taken  by  the  ice  the  structure  and  building  of  the 
state  must  be  kept  clearly  in  mind;  as  shown  in  the  first  two  chapters, 
it  is  essentially  a  core  of  hard,  crystalline  rocks,  which  forms  today 
the  highest  portion  of  the  state,  flanked  by  successive  layers  of  alter- 
nately harder  and  softer  rocks,  which  are  so  tilted  that  they  outcrop 
on  the  surface  in  successive  parallel  ridges.  Already  before  the 
glacial  age  the  softer  layers  had  been  excavated  by  the  rivers  into 
lowlands  and  the  harder  layers  stood  up  as  cuesta  ridges. 

Both  the  earlier  and  the  later  sheets  were  divided  into  lobes  by 
the  irregularities  of  the  ground  over  which  they  passed,  but  the  record 
of  the  first  sheet  is  much  obscured  by  the  deposits  from  the  last  one, 
which  passed  over  much  the  same  territory. 

So  far  as  can  be  made  out  the  history  of  the  two  sheets  is  some- 
what similar.  The  ice  of  the  first  invasion  advancing  in  a  generally 
southwest  direction  from  the  point  of  its  origin  southeast  of  Hudson's 
Bay  encountered  the  highlands  of  hard,  igneous  rock  which  form 
the  main  portion  of  northern  Wisconsin  and  the  upper  peninsula  of 
Michigan  and  at  the  same  time  entered  the  two  great  valleys  which 
are  now  the  beds  of  Lakes  Michigan  and  Superior.  As  the  advancing 
ice  met  the  barrier  of  hard  rocks,  which  it  could  not  easily  surmount 
nor  remove  readily  by  erosion,  it  was  deflected  down  the  convenient 
valleys  in  two  great  diverging  lobes.  The  western  one  passed  almost 
directly  west  through  the  basin  of  Lake  Superior,  probably  giving  it 
much  of  its  present  shape  in  its  passage,  and  emerging  from  the  west- 
ern end  turned  southwest  again,  and  continued  imtil  it  reached  far 
south  of  the  present  southern  line  of  the  state.  The  eastern  portion 
of  the  divided  mass  continued  almost  directly  south  in  the  basin  of 
Lake   Michigan  and  when   well   south   of  the   state   spread   out   to   the 


15 

west  until  the  edges  of  the  two  lobes  met  in  the  vicinity  of  Dubuque. 
During  some  portion  of  the  invasion  the  ice  succeeded  in  passing  the 
highlands  to  the  north  and  advanced  as  a  short  lobe  over  the  central 
portion  of  the  state  as  far  south  as  Grand  Rapids,  approximately. 

The  ice  of  the  Wisconsin  sheet  has  left  a  much  clearer  record 
in  the  form  of  striations  on  the  rocks,  moraines  and  altered  drainage 
lines.  Advancing  from  the  northeast  the  ice  was  divided  by  the  same 
elevated  region  of  hard  rocks  as  was  the  ice  of  the  first  invasion 
and  split  into  a  mass  which  passed  down  the  Michigan  trough  and 
one  which  headed  westward  in  the  Superior  trough.  These  separate 
masses  probably  found  the  guiding  lake  basins  much  deeper  than 
did  the  first  ice,  for  there  is  no  doubt  that  though  the  ice  felt  the 
guidance  of  the  preglacial  topography  it  shaped  and  molded  the  hills 
and  valleys  as  it  passed. 

The  large  lobe  that  moved  southward  in  the  valley  of  Lake 
Michigan  was  again  subdivided  into  smaller  lobes;  a  larger  which  con- 
tinued straight  south  and  is  known  as  the  Michigan  lobe,  and  a 
smaller  which  moved  somewhat  to  the  southwest  and  is  known  as  the 
Green  Bay  lobe.  The  ice  of  these  two  lobes  extended  down  two  pre- 
glacial lowlands,  the  Michigan  lowland  on  the  east  and  the  Green 
Bay  lowland  on  the  west,  and  that  they  were  divided  on  the  north 
by  the  hard  rocks  of  the  Niagara  cuesta,  which  projects  out  between 
Green  Bay  and  Lake  Michigan  as  the  Door  peninsula  and  can  be 
traced  farther  north  in  Washington  Island,  Rock  Island,  Great  Gull 
Island  and  a  ridge  which  continues  beneath  the  water  and  is  revealed 
only  by  soundings. 

A  small  lobe  extends  from  the  western  side  of  the  Michigan  lobe, 
near  the  southern  border  of  the  state;  from  its  relation  to  the  lake 
of  that  name  it  is  known  as  the  Delavan  lobe. 

The  Superior  mass  spread  to  west  as  in  the  earlier  invasion,  but 
the  movement  of  the  ice  was  so  great  that  part  of  it  was  forced  up 
the  north  slope  of  the  highlands  and  down  the  other  side;  as  it  left 
the  valley  of  Superior  it  encountered  the  hard  rocks  of  the  Bay- 
field peninsula,  which  divided  it  into  two  parts,  just  as  the  Door 
peninsula  divided  the  Michigan  lobe,  the  part  to  the  east  extended 
only  a  short  distance  to  the  south,  invading  the  region  which  is  now 
about  the  headwaters  of  the  Chippewa  river  and  has  so  been  called 
the  Chippewa  lobe.  The  western  portion  of  the  Superior  lobe  ex- 
tended out  of  the  western  end  of  the  Superior  trough  and  turned 
southward  as  the  Superior  lobe;  it  covers  portions  of  Minnesota, 
Iowa  and  Illinois,  as  well  as  Wisconsin.  As  in  the  case  of  the  first 
invasion,  the  Michigan  and  Superior  lobes  passed  around  the  southern 
end   of   the   state,   and   the   middle,   Chippewa,   lobe   did   not   reach   far 


16 

south  of  Wausau,  so  that  the  southwestern  corner  of  the  state  has 
never  been  touched  by  the  ice,  though  it  is  well  within  the  limits  of 
the  glaciated  portion  of  the  United  States;  this  is  the  celebrated 
Driftless  Area  of  Wisconsin. 

Another  lobe  of  glacial  ice  just  touched  the  borders  of  the  state 
on  the  west,  in  the  vicinity  of  St.  Croix  Falls,  but  this  one  was  very 
dififerent  in  origin  from  those  which  covered  most  of  the  state,  for  it 
had  its  birth  in  the  great  Keewatin  sheet,  which  developed  west  of 
Hudson's  Bay  and  advancing  to  the  south  covered  the  state  of  Min- 
nesota, North  Dakota  and  South  Dakota.  The  portion  of  this  sheet, 
which  advanced  across  Minnesota  to  the  border  of  Wisconsin,  is 
sometimes  called  the  Minnesota  lobe  and  sometimes  the  Red  River 
lobe.  This  lobe  of  the  western  ice  sheet  and  the  Superior  lobe  of  the 
eastern  sheet  met  on  the  line  between  the  states  of  Wisconsin  and 
Minnesota  and  have  left  their  recoras  in  mingled  confusion. 

The  Terminal  Moraine  in  Wisconsin  is  quite  generally  referred 
to  as  the  Kettle  moraine.  As  would  be  expected  from  its  origin,  the 
topography  is  rough  and  irregular  in  the  extreme;  sharp,  steep-sided 
hills  alternate  with  deep,  steep-sided  holes  which  have  no  outlet  and 
may  contain  ponds  or  swamps  or  be  entirely  dry.  There  is  no  regu- 
lar arrangement  in  lines  or  otherwise  of  the  hills  and  valleys  and  the 
drainage  is  very  imperfect;  every  feature  tells  of  the  violent  origin. 
The  deep,  steep-sided  holes  appeared  to  the  first  describers  to  re- 
semble the  large  kettles  used  in  the  early  days  in  making  lye  and 
soap,  and  so  they  were  referred  to  as  the  "Potash  kettles"  or  "kettles" 
and  the  name  gradually  spread  to  the  whole  ridge. 

The  moraine  enters  the  state  from  Illinois  in  Kenosha  county, 
not  far  from  the  lake  shore,  and  extends  slightly  west  of  north  to  the 
vicinity  of  Burlington,  where  it  turns  sharply  to  the  southwest,  mark- 
ing the  position  of  the  division  of  the  Alichigan  glacial  lobe  called  the 
Delavan  lobe;  completing  the  small  semicircle  in  Walworth  county 
around  Lakes  Geneva  and  Delavan,  which  marks  the  extent  of  the 
Delavan  lobe,  the  moraine  of  the  ^Michigan  lobe  joins  that  of  the 
Green  Bay  lobe  just  north  of  the  village  of  Richmond,  Walworth 
county,, a  few  miles  south  of  Whitewater.  From  the  point  of  union 
a  strong  ridge  runs  northeast  across  the  state  almost  to  the  ex- 
tremity of  the  Green  Bay  peninsula.  From  Richmond  the  Green  Bay 
moraine  runs  almost  straight  north  to  a  point  a  few  miles  northeast 
of  Antigo,  in  Langlade  county,  where  a  sharp  re-entrant  angle  marks 
the  union  of  this  moraine  with  that  of  the  Chippewa  lobe.  As  in  the 
case  of  the  Lake  Michigan  and  Green  Bay  moraines  a  ridge  runs  back 
northeast  from  the  point  of  union,  marking  where  the  sides  of  the 
two  lobes  met.     The  terminal  moraine  of  the  Chippewa  lobe   extends 


17 

south  and  west  in  a  great  curve  through  Lincoln  and  Taylor  counties 
until  it  meets  the  moraine  of  the  Superior  lobe  in  Washburn  county. 
Here  again  a  re-entrant  angle  and  a  northeasterly  projecting  ridge 
marks  the  meeting  of  the  sides  of  the  two  lobes.  The  moraine  of  the 
Superior  lobe  passes  southwest  and  out  of  the  state  in  the  southwest 
corner  of  St.   Croix  county. 

The  origin  of  the  Green  Bay  and  Lake  Michigan  lobes  has  already 
been  described  and  the  influence  of  the  preglacial  basin  of  Lake  Michi- 
gan and  the  Green  Bay  lowland  in  directing  their  course  pointed  out; 
but  while  the  main  motion  of  the  lobes  was  to  the  south  they  were 
at  the  same  time  expanding  in  a  less  degree  to  the  sides,  so  that  the 
two  lobes  were  overriding  the  sides  of  the  channels  which  directed 
them.  As  the  sides  of  the  lobes  advanced  in  a  direction  more  or  less 
at  a  right  angle  to  the  main  motion  they  gathered  in  front  of  them 
and  pushed  ahead  a  terminal  moraine  in  all  respects  identical  in  char- 
acter wnth  the  terminal  moraine  at  the  front  of  the  lobe;  as  the  two 
lobes  expanded,  one  to  the  west  from  the  basin  of  Lake  Michigan 
and  one  to  the  east  from  the  valley  of  Green  Bay,  the  two  sides  and 
the  moraines  ahead  of  the  sides  came  together  near  the  middle  of  the 
Green  Bay  peninsula  and  farther  south  to  the  point  where  the  ter- 
minal moraines  meet  at  Richmond.  Because  of  the  origin  of  this 
branch  of  the  kettle  moraine  it  has  been  called  an  Interlobate  mo- 
raine. As  shown  above,  interlobate  moraines  also  mark  the  line  of 
meeting  of  the  Green  Bay  and  Chippewa  and  the  Chippewa  and  Su- 
perior lobes,  but  neither  of  the  two  is  so  well  marked  or  preserved 
as  the  one  in  eastern  Wisconsin. 

On  the  western  side  of  the  state  there  is  a  considerable  area  be- 
tween the  terminal  moraine  and  the  driftless  area  which  is  occupied 
by  deposits  from  the  ice  of  the  earliest  invasion.  There  are  here  all 
the  features  of  the  drift-covered  region,  but  in  a  much  modified  form, 
for  they  are  much  older  and  the  forces  of  degradation  have  been 
much  longer  at  work  upon  them  and  have  reduced  them  much  farther 
toward  the  original  condition.  The  shape  of  this  region  shows  that 
it  was  covered  by  a  lobe  of  the  ice  very  similar  to  the  Chippewa 
lobe  of  the  last  invasion;  its  terminal  moraine  leaves  the  terminal 
moraine  of  the  last  invasion  somewhere  north  of  Wausau  and  runs 
southwest  into  Clark  county  and  then  curves  northwest  into  Chippewa 
county  and  southwest  again  into  Pierce  county  and  so  out  of  the  state. 
A  somewhat  similar  area  appears  in  the  extreme  southeastern  part 
of  the  south  of  the  terminal  moraine  of  the  Green  Bay  lobe  of  the 
Glacier. 

The  Driftless  Area. — This  lies  in  the  southwestern  and  western 
parts  of  the  state  and  includes  narrow  strips  of  the  adjacent  parts  of 


18 

the  states  of  Illinois,  Iowa  and  Minnesota.  Its  northern  edge  is 
indented  by  the  convex  terminal  moraine  of  the  region  of  earlier 
drift  and  on  either  side  of  this  it  sends  sharp  processes  to  the  north. 
Its  general  outline  is  shown  in  figure  4.  Surrounded  on  all  sides  by 
glaciated  country,  it  furnishes  to  the  student  of  the  state  and  of 
glaciology  in  general  a  mass  of  most  valuable  comparative  material, 
for  it  shows  the  topography  of  an  older  land  in  an  advanced  stage  of 
degradation  immediately  adjacent  to  regions  which  in  the  latest 
geological  period  has  been  covered  by  new  deposits,  now  in  the  ear- 
liest stages  of  degradation.  It  is  impossible  to  even  list  the  theories 
that  have  been  advanced  to  explain  why  this  region  was  not  visited 
by  the  ice,  so  that  only  one,  that  advanced  by  Chamberlin  and  quite 
generally  accepted,  will  be  reproduced  here. 

The  driftless  area  lies  between  the  great  depression  of  the  Lake 
Superior  basin  on  the  north  and  that  of  the  Lake  Michigan  basin  on 
the  east,  with  the  highlands,  composed  of  hard,  crystalline  rocks, 
directly  to  the  north  and  northeast.  Lake  Superior  has  an  average 
depth  of  about  1,000  feet;  its  surface  is  about  600  feet  above  the  level 
of  the  sea;  the  summit  of  the  highlands  30  to  40  miles  to  the  south 
is  about  1,200  feet  above  the  level  of  the  lake,  so  there  is  a  difference 
of  about  2,200  feet  from  the  bottom  of  the  lake  basin  to  the  top  of 
the  highlands.  Lake  Michigan  has  an  average  depth  of  900  feet  and 
its  surface  is  nearly  on  a  level  with  that  of  Lake  Superior,  so  there  is 
a  difference  of  about  2,100  feet  from  the  bottom  of  the  lake  to  the 
summit  of  the  highlands  to  the  west.  If  the  lakes  were  drained  it 
is  seen  that  the  highlands  would  constitute  a  very  considerable  eleva- 
tion between  them  with  a  long  slope  to  the  south,  including  most  of 
the  state  of  Wisconsin  and  good  parts  of  the  rreighboring  states  of 
Illinois,  Iowa,  Missouri  and  Minnesota.  It  is  probable  that  the  ice 
advancing  from  the  northeast  was  split  by  the  hard  rocks  of  the 
upper  peninsula  of  Michigan  and  advanced  around  the  highland  in 
the  form  of  lobes  which  clung  to  the  depressions  of  the  lake  basins, 
but  in  the  forward  movement  the  ice  was  gradually  crowded  up  and 
over  the  obstructing  highlands,  and  in  the  time  of  the  maximum  for- 
ward movement  of  the  ice  crept  down  the  face  of  the  southern 
slope  in  what  is  called  the  Chippewa  lobe.  But  why,  having  once 
surmounted  the  barrier,  did  not  the  ice  descend  the  southern  slope 
as  rapidly  and  as  far  as  the  Michigan  and  Superior  lobes?  Perhaps 
for  two  main  reasons.  According  to  Chamberlin  the  ice  surmounted 
the  barrier,  2,100  to  2,200  feet  high,  only  when  it  was  at  its  greatest 
advance,  and  from  then  on  its  forward  movement  was  less  rapid; 
moreover,  the  forward  movement  of  the  ice  was  greatly  retarded  as 
it  pushed  over  the  hills  and  was  much  slower  than  that  of  the  other 


19 

lobes.  Again  the  maximum  of  forward  movement  was  coincident 
with  the  culmination  of  the  Ice  age,  and  thereafter  the  climate  became 
slowly  warmer;  the  ice,  creeping  down  a  long  southern  slope,  was 
exposed  to  the  full  power  of  the  sun  and  it  is  probable  that  the  rate 
of  melting  was  faster  there  than  on  the  other  lobes  and  faster  than 
the  rate  of  advance.  The  stronger  Superior  and  Michigan  lobes  did 
not  waste  by  melting  so  rapidly  because,  instead  of  being  thinned  by 
spreading  out,  they  were  more  confined  in  the  narrower  basins  and 
thickened  by  accumulation,  so  that  they  advanced  more  rapidly  than 
they  were  destroyed  by  melting.  It  is  also  probable  that  the  lobes 
assisted  in  their  own  perpetuation,  for  large  masses  of  snow  or  ice, 
by  chilling  the  air  which  blows  upon  them,  induce  an  increased  pre- 
cipitation; so  these  lobes  may  have  chilled  the  moisture  laden  air 
from  the  south  or  from  the  driftless  area  and  caused  abundant  snow- 
falls upon  their  surface. 

Says  Chamberlin:  "Divided  by  the  Highlands,  led  away  by  the 
valleys,  consumed  by  wastage  where  weak,  self-perpetuated  where 
strong,  the  fingers  of  the  mer  de  glace  closed  around  the  ancient 
Jardin  of  the  Upper  Mississippi  valley,  but  failed  to  close  upon  it." 

These  models  are  made  by  the  Central  Scientific  Co.,  of  Chicago,  14-28  Michigan 
street.    Information    regarding    them    may    be    obtained   from  Mr.  Case,  or  from  the 

Central  Scientific  Company. 


1  i  b 


iX>^  A.iSl»ti-fc,i>,  C.A>-lh, 


Lithomount 

Pamphlet 

Binder 

Gaylord  Bros. 

Makers 

Syracuse,  N.  Y. 


